The 340 F/A, 440 F/C and RV were available, but the problem plagued 440 F/A was dropped from the line. Other than some minor cosmetic changes like color and decals, the T'NT models were fundamentally unchanged from the previous year. It would be the final year for the RV but its incredible handling chassis would be use on the 1978 and 1979 Blizzard's.
With the introduction of the RVCC in 1977, the racing associations started thinking about using horsepower instead of displacement as a means of classifying sleds. A 45hp limit, plus or minus 10 percent, was used for cross country racing. The RVCC 345 engine almost made that in one cylinder. With the limit on horsepower the 345 could not be used. So the 1978 RVCC used a free air cooled 345, with Nikasil cylinders and heads from the 1976 modified kit. A single tuned exhaust was used to drop the RVCC into the new horsepower limit. Only 250 of these were produced. With the right combination of weight and chassis setup the RVCC dominated cross- country racing for years.
This was the last year for the T'NT, but with some of the advances it produced in snowmobile technology and thousands of wins on the tracks. Many of the same concepts first presented on the T'NT models live on today. Eleven years of T'NT's produced a lot of "First"!